November 08, 2012

Okinawans and admixture in East Asia

I don't use the Pan-Asian SNP Consortium data much, but the upcoming paper on the Ainu spurred me to give it a look, because it contains an Okinawan sample (JP-RK). I calculated all f3-statistics that involved this sample, and report the lowest f3-statistic for all populations in this set that appear to be admixed:

Several of these are interesting:

A set of Indonesian populations (ID prefix; Lamaholot, Lembata, Kambera, Manggarai) are mixed with Melanesians (AX-ME)

A set of Indian populations appear admixed (IN prefix). It seems that the Okinawan sample acts as a surrogate for "Asian" ancestry

Filipino populations PI-UI and PI-UN (listed as Visaya, Chabakano and Tagalog) are seen as mixtures of Okinawans and PI-UB (Ilocano)

The three Singaporean populations (SG prefix) are seen as mixtures with Caucasoids (the SG-ID Tamil Indians with CEU), with Sunda Indonesians (SG-ML Malay with ID-SU), with Zhuang Chinese (SG-CH Singaporean Chinese with CN-CC Zhuang, northern)

And, of course JPT and JP-ML (Japanese) are seen as a mixture of Okinawans and Mandarin Han (CN-SH) and Beijing Chinese (CHB).

An interesting question is whether the mainland East Asian Yayoi element in Japanese is more similar to Han (as the f3 statistic suggests) or to Koreans. Interestingly, Koreans themselves (KR-KR) appear admixed between Han (CN-SH) and Okinawans. So, it seems that whatever this Okinawan element represents was not limited to the isles of Japan.

I also calculated the D-statistic:

D(CN-SH KR-KR : JP-RK YRI) = -0.0154 (Z = -14.779)

which suggests indeed, that there is an excess of "Okinawan"-like ancestry in Koreans compared to the Chinese. This is very interesting, because it suggests that similarity between Koreans and Japanese is due to a common substratum in the two populations.

Okinawans are already mixed with Yayoi and aren't 100% Jomon (more like 50% Jomon). Hence the "Okinawan" component in Koreans is most likely derived from the Yayoi component, not the Jomon component.

Furthermore, the Gaya who resided in the southern part of Korea spoke a language which is most related to the Japonic languages according to Christopher Beckwith. The Gaya most likely invaded parts of southern Japan and Okinawa before entering Honshu.

The history of Okinawa is complex. It is likely that the Okinawans are mixed with Koreans, Yayoi and other populations. The Koreans also had their own paleolithic population but whether they were related to the Jomon is unknown (probably not because of the lack of Y-DNA haplogroup D chromosomes in Korea - <5%).

That is not surprising if we are prepared to accept that the 'original' population of Indonesia was of 'Papuan' phenotype and that the 'Mongoloid' phenotype is a result of Neolithic movement into the region from further north. Parts of Indonesia, especially Southern Wallacea, still preserve strong elements of that 'Melanesian' phenotype. Of course this conflicts with the generally accepted idea that the Mongoloid phenotype is of ancient presence in SE Asia.

CN-SH are actually those from the Wu speaking region known as Jiangnan. Shanghainese natives are mostly from the surrounding Jiangnan region that speak a language known as Shanghainese or Jiangnanese. CHB is the Northern Mandarin-speaking population.

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